DESCRIPTION
WIRING DIAGRAM
INSPECTION PROCEDURE
CHECK FOR SHORT IN CAN BUS LINES (DLC3 BRANCH LINE)
RECONNECT CONNECTOR
CHECK FOR SHORT IN CAN BUS LINES (BRANCH LINE)
CHECK FOR SHORT IN CAN BUS LINES (GATEWAY ECU MAIN BUS LINE)
CHECK FOR SHORT IN CAN BUS LINES (ECM MAIN BUS LINE)
CHECK CAN LH J/C
RECONNECT CONNECTOR
CHECK CAN RH J/C
RECONNECT CONNECTOR
CHECK FOR SHORT IN CAN BUS LINES
RECONNECT CONNECTOR
CHECK FOR SHORT IN CAN BUS LINES (GATEWAY ECU)
RECONNECT CONNECTOR
CHECK FOR SHORT IN CAN BUS LINES (ECM)
CAN COMMUNICATION SYSTEM (for LHD) - Short in CAN Bus Lines
DESCRIPTION
The CAN bus lines are considered to be shorted when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.
| Symptom | Trouble Area |
| Resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω. | Short in CAN bus lines
Skid control ECU
Steering angle sensor
Yaw rate sensor
ECM
Gateway ECU
Seat belt control ECU
Distance control ECU
Power steering ECU
Television camera ECU
Center airbag sensor
CAN LH J/C
CAN RH J/C
|
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.CHECK FOR SHORT IN CAN BUS LINES (DLC3 BRANCH LINE) |
Turn the engine switch off.
Disconnect the DLC3 branch line connector (J8) from the CAN LH J/C B side (without earth terminal).
Before disconnecting the connector, make a note of where it is connected.
Reconnect the connector to its original position.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 1 MΩ or higher |
| 4.CHECK FOR SHORT IN CAN BUS LINES (GATEWAY ECU MAIN BUS LINE) |
Disconnect the gateway ECU main bus line connector (J84) from the CAN RH J/C B side (without earth terminal) .
Before disconnecting the connector, make a note of where it is connected.
Reconnect the connector to its original position.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 108 to 132 Ω |
- Result:
| Symptom | Proceed to |
| The resistance is still below 54 Ω when the gateway ECU connector is disconnected. (There are no shorts in the gateway ECU main bus lines.) | A |
| The resistance falls within the specified range (between 108 and 132 Ω) (either of the terminating resistances is normal) when the gateway ECU connector is disconnected. (There is a short in the gateway ECU main bus lines.) | B |
| 5.CHECK FOR SHORT IN CAN BUS LINES (ECM MAIN BUS LINE) |
Disconnect the ECM main bus line connector (J2) from the CAN LH J/C A side (with earth terminal) .
Before disconnecting the connector, make a note of where it is connected.
Reconnect the connector to its original position.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 1 MΩ or higher |
- Measure the resistance with the gateway ECU main bus line connector (J84) disconnected.
- Result:
| Symptom | Proceed to |
| The resistance is still below 1 MΩ when the ECM connector is disconnected. (There are no shorts in the ECM main bus lines.) | A |
| The resistance becomes 1 MΩ or more when the ECM connector is disconnected. (There is a short in the ECM main bus lines.) | B |
Disconnect the CAN main bus line connector (J7) from the CAN LH J/C B side (without earth terminal).
Before disconnecting the connector, make a note of where it is connected.
Reconnect the connector to its original position.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 1 MΩ or higher |
Reconnect the CAN main bus line connector (J7) to the CAN LH J/C B side (without earth terminal).
Disconnect the CAN main bus line connector (J81) from the CAN RH J/C A side (with earth terminal) .
Before disconnecting the connector, make a note of where it is connected.
Reconnect the connector to its original position.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 1 MΩ or higher |
| NG | |
| |
| REPAIR OR REPLACE CAN MAIN BUS LINE (CAN LH J/C - CAN RH J/C) |
|
Reconnect the connector for the short-circuited branch line to the CAN J/C (the connector that caused the bus line resistance to become normal (between 54 and 69 Ω) when it was disconnected).
| 10.CHECK FOR SHORT IN CAN BUS LINES |
Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the short-circuited branch line is connected.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 1 MΩ or higher |
- If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).
| | REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINE OR CONNECTOR |
|
|
| OK | |
| |
| REPLACE CORRESPONDING ECU OR SENSOR |
|
Reconnect the gateway ECU main bus line connector (J84) to the CAN RH J/C B side (without earth terminal) .
| 12.CHECK FOR SHORT IN CAN BUS LINES (GATEWAY ECU) |
Disconnect the gateway ECU connector (J76).
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 108 to 132 Ω |
- If the resistance becomes normal (between 108 to 132 Ω) when the connector is disconnected, there may be a short in the gateway ECU.
| | REPAIR OR REPLACE CAN MAIN BUS LINE (GATEWAY ECU MAIN BUS LINE) |
|
|
Reconnect the ECM main bus line connector (J2) to the CAN LH J/C A side (with earth terminal).
| 14.CHECK FOR SHORT IN CAN BUS LINES (ECM) |
Disconnect the ECM connector (A5).
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
| Tester Connection | Condition | Specified Value |
| J21-6 (CANH) - J21-14 (CANL) | Engine switch off | 1MΩ or higher |
Measure the resistance with the gateway ECU main bus line connector (J84) disconnected.
If the resistance changes to 1 MΩ or more when the connector is disconnected, there may be a short in the ECM.
| | REPAIR OR REPLACE CAN MAIN BUS LINE (ECM MAIN BUS LINE) |
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LEXUS IS250, IS220d / GSE20 ALE20
